Eren Yeager was the main protagonist (and paradoxically, final villain) of the Attack On Titan series. Throughout the countless battles he has fought, his ultimate objective has always been with Paradis' greater interest in mind.
After absorbing the War Hammer Titan (and even before mastering the Founder), he was a force that few could contend with. Through identifying those in the series he could defeat and the few still beyond his ability, we can better appreciate his merits as a warrior and the ways that he has improved over time.
10 COULD BEAT: Mikasa Is Formidable But Held Back By Sentiment & Love For Eren
Mikasa may have been a scout on par with Levi and one of the greatest non-titan shifters that could potentially defy Eren, but the powerful feelings she harbors for him would be too much to navigate in the midst of battle in most situations.
This was primarily demonstrated in the Yeagerist takeover when Armin attempted to assault Eren for having insulted her. Because Mikasa pinned him down before she had even realized it, it follows that she'd hesitate in the midst of a climactic battle with her paramour and be cut down due to her indecision.
9 WOULD LOSE TO: Ymir Has Mastered The Power Of The Nine Titans & Is The True Wielder Of The Founder
The Founding Titan's power was derived from Ymir, who was bound to the Fritz family out of love and devotion. She was the first character to single-handedly wield the might of all nine titan shifters, with her blessing being passed down to her daughters after her death.
Towering far above even the Colossal and having once conquered most of the world by herself, she would easily overwhelm Eren in spite of his martial abilities and clever usage of the War Hammer titan's spikes.
8 COULD BEAT: Eren Has Defeated Reiner Even Before Inheriting The War Hammer
Reiner's armor renders him impervious to the traditional blades of scouts, but it also encumbers him considerably and reduces his mobility. After Eren learned how to crystallize and harden any part of his body, he gained a massive advantage in agility over Braun and was able to wrestle him to the ground.
Considering that Eren would have defeated Reiner after the battle for Utgard if Bertholdt hadn't intervened (and given the results of their second fight during the war for Marley), the Armored Titan is doomed to lose their fight.
7 WOULD LOSE TO: Levi Would Be Able To Stay Out Of Eren's Range & Strike Out His Nape
Unlike Mikasa, Levi was fully prepared to kill Eren and is even more qualified to do so. He was fast enough to adapt to pure titans even when they caught them by surprise, suggesting that he could remain well out of reach from Yeager's attacks just as well as Porco did.
While Eren is intelligent enough to guard his nape, Levi would divert his attacks to his eyes and joints instead so that the villain was forced to revert to his human form.
6 COULD BEAT: Sasha Lacks The Explosive Force Necessary To Take Eren Down
Surprisingly, Sasha would be better equipped to defeat Eren than most of the series' other scouts. She was precise enough to bounce arrows off of the interior of bunkers, killing the intended targets inside. The marksman additionally managed to snipe Kenny's men from across the battlefield, meaning that she could shoot out Eren's eyes with similar success.
However, the War Hammer was capable of creating spiky columns that covered a wide surface. Even if Eren was blinded and missed his original attack, he could re-transform in order to locate Braus and end her life.
5 WOULD LOSE TO: Armin Could Ignore Eren's Comparatively Inconsequential Attacks & Crush Him
Although Eren proved a difficult adversary for Armin to overcome after his skeletal transform, he'd be no match for him before then. Arlert's initial detonation would create an explosion powerful enough to deplete Eren's titan body, forcing him to make another one if he wished to continue the fight.
While the War Hammer's spikes might cause minor injuries to Armin's legs, it could not amputate him nor prevent Eren from being punted into the ground as he was during his fight against Bertholdt.
4 COULD BEAT: Porco Has An Advantage In Speed But Possesses Pathetic Durability
The Jaw Titan was perhaps the only shifter aside from Pieck who could efficiently and repeatedly dodge Eren's attacks. This was proven during the Marleyan invasion of Paradis, where he ducked away from a point blank punch and even obviated the War Hammer's spike ability.
However, he is an exclusively melee combatant with low durability. Either he must confront Eren directly by leaping toward him and be pummeled into the ground or flee and live to fight another day.
3 WOULD LOSE TO: Lara Tybur Was Much Better At Using The War Hammer Than Eren Was
Although Eren defeated Lara in the canon series, it was only because Mikasa provided the distraction (and thunder spears) that enabled him to do so. Tybur proved a more efficient user of her abilities than her Eldian adversary, as illustrated on numerous occasions.
Not only did she wield weapons more naturally (such as hammers, swords, and even bows), but she was also surrounded by a protective crystal cocoon. If Eren managed to defeat her, he'd have no means of killing her before she regained the strength to fight again since Porco is not nearby.
2 COULD BEAT: Eren Used Annie's Skills Against Her
Annie Leonhart may have dominated Eren in their first forest engagement, but their second fight within the walls of Shiganshina produced a different result. By learning from her fighting style and adapting it as his own, he used superior size, strength, and ferocity to bring the Marleyan spy down.
Now that he has the boon of the War Hammer titan, the fight would be even more lopsided in his favor.
1 WOULD LOSE TO: Eren Has Nothing In His Arsenal That Could Defeat The Reiss Titan
The Reiss Titan was twice as large as the Colossal and secreted the same boiling steam as its diminutive counterpart. Posing an unprecedented risk at close range, Eren was only able to defeat it with the aid of scouts and dozens of explosive barrels.
Without these advantages, Eren is far outmatched in durability, strength, and reach. If he were to have the faceless monstrosity's undivided attention, he could not hope to destroy the nape of its neck with his War Hammer protrusions before being crushed into pulp.